Fiber optic cable harnesses consist of a plurality of individual fiber optic cables of indeterminate length which are bundled together. Interconnections between adjacent cable harnesses are made by connector assemblies which consist of multi-contact, separable connectors and their strain relief adapters, which are commonly referred to as "backshells." The backshells include protective housings through which the fiber optic cables are passed, so that a terminus end of each fiber optic cable is precisely positioned at one end of the connector and properly aligned for abutment with a corresponding fiber optic cable in a mating connector of another cable harness, or of an instrument which uses transmissions from the fiber optic cables. The connector's threaded interconnecting joint is used to properly position the adjoining fiber optic cable ends relative to each other. The individual cables are restrained against longitudinal movement relative to the connection and relative to the respective cables to which they are interconnected. The aforesaid cable restraint is provided by an elastomeric grommet which is compressed within the cable entry end of the backshell. The individual fiber optic cables are threaded through individual passages in the grommet. When the cable end coupling ring portion of the backshell is tightened, the grommet is compressed so as to grip and restrain each of the fiber optic cables against longitudinal movement. Thus in each backshell the grommet will grip the fiber optic cables at a location spaced from their cut ends.
The aforesaid connector assembly system is similar to that used to interconnect conventional electrical cables, and has proven to be quite serviceable with conventional electrical cables. A problem, however, arises when the aforesaid connector assembly is used with fiber optic harnesses due to the fragile nature of fiber optic cables. The problem resides in the fact that the end of the backshell that contains the free ends of the individual fiber optic cables can be intentionally or accidentally rotated without loosening the grommet which grips the individual fiber optic cables. Such rotation is typically attempted in order to align the cables with the intended direction of the harness routing. The result is that the fiber optic cables will be restrained against longitudinal movement at a location distal of their free ends, and will be twisted at their free ends. This imparts a longitudinal displacement and a resultant stress on the fiber optic cables which can break them or damage their connections. Obviously, breakage of any of the individual fiber optic cables and connection damage are undesirable, and will result in system malfunctions.